Dresden 2011 – scientific programme

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MO: Fachverband Molekülphysik

MO 19: Cold Molecules III

MO 19.3: Talk

Wednesday, March 16, 2011, 17:00–17:15, BAR Schön

Threshold photodetachment thermometry for cold molecular anions — •Alexander von Zastrow¹, Thorsten Best¹, Rico Otto¹, Stephanie Eisenbach¹, Martin Stei³, Sebastian Trippel¹, Matthias Weidemüller², and Roland Wester³ — ¹Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg — ²Physikalisches Institut, Universität Heidelberg, Philosophenweg 12, 69120 Heidelberg — ³Institut f. Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, A-6020 Innsbruck

During photodetachment an anion’s excess electron is lifted from a bound to a continuum state. The cross section for this process reveals information about the internal structure of the anion and the neutral as well as long range electron-neutral interactions. One of the best studied molecular anions is OH⁻. At threshold the photodetachment cross section is sensitive to the different occupied rotational levels. From their contribution to the cross section, the anions’ rotational temperature can be derived. In our experiments ions are stored and sympathetically cooled in a 22-pole radiofrequency trap which can be operated between 8 K and 300 K. To determine the ions’ rotational temperature, we measure the absolute photodetachment cross section using a previously reported laser depletion tomography method [1,2]. This will allow us to investigate the efficiency of collisional cooling of internal degrees of freedom in future experiments.
S. Trippel et al., Phys. Rev. Lett. 97, 193993 (2006)
P. Hlavenka et al., J. Chem. Phys. 130, 061105 (2009)